0db6820b10
The CPU can arbitrarily reorder calls to rdtsc, significantly reducing the precision of timing using the CPUs time stamp counter. Unfortunately the method of synchronizing rdtsc is different on AMD and Intel CPUs. There is a generic method, using the cpuid instruction, but that uses up a lot of registers, and is very slow. Hence, use the correct lfence/mfence instructions (for CPUs that we know support it) Change-Id: I17ecb48d283f38f23148c13159aceda704c64ea5 Signed-off-by: Stefan Reinauer <reinauer@google.com> Reviewed-on: http://review.coreboot.org/1422 Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com> Tested-by: build bot (Jenkins) |
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| amd | ||
| intel | ||
| x86 | ||
| cpu.h | ||